Technical Field
This disclosure relates to the field of object recognition for user interface devices.
Description of the Related Art
Touch screens may utilize a variety of different sensor technologies, such as resistive, capacitive, inductive, and radio frequency sensor arrays. Resistive touch screens, in particular, are well suited for use with passive styluses, as resistive touch screens are able to sense an input from nearly any object. However, resistive touch screens are limited in regard to sensing multiple objects at the same time. For example, multi-touch (i.e., applying two or more objects to the touch screen simultaneously) is generally not supported by resistive touch screens. Due to this and other limitations, other types of touch screens, such as capacitive touch screens, are increasingly replacing resistive touch screens in the consumer marketplace.
One of the major challenges for touch screens that support multi-touch is object recognition. Current touch screens have difficulty distinguishing between a user's hand, such as a palm or finger, and a passive stylus. Proper object recognition is important in order to execute respective procedures for different types of touch objects.
Object recognition is particularly important along edges of a touch screen as the edges are often subject to inadvertent contact. For example, when a user holds a touch screen device, such as a phone or a tablet, the user's palm or finger will often incidentally contact an edge of the touch screen and cause a false detection of a passive stylus. The incidental contact of the user's hand on the touch screen is sometimes referred to as grip shadow. Unfortunately, differentiating between a user's hand and a passive stylus along an edge of a capacitive touch screen is often difficult, as sensing data along edges is typically minimal.